Facsimile recording system and apparatus



May 29; 1945.

FACSIMILE RECORDING SYSTEM AND APPARATUS RQ J. WISE Fi1ed Nov. 27.' l1941 FIG. l

2 Sheets-Sheet l zoo INVENTOR R. J. WIS E BY www,

ATTORNEY .......QI wwfwwn R. j. WISE May 29, 1945.

FACSIMILE BECRDING sYST EM AND- APPARATUS Filed Nov. 27, 1941` 2 Sheets-Sheet 2 FIG. 2V

INVENTOR R J WISE.

vATTORNEY Patented May 1945 APPARATUS Raleigh J. Wise, Dunellen, N. J., assignor to The Western Union Telegraph Company, New York` N. Y., a corporation of New York Application Nevember 21, 1941, serial No. 420,610

14 Claims.

This invention relates to an improved'system and apparatus for reproducing facsimile copies of pictures, drawings, writing .and other subject matter, and is particularly adapted, although not limited thereto, to the production of a master copy of an original, from which numerous other copies vmay be made by the mimeograph, hectograph,

and other Vprinting processes.

In accordance with the present invention a picture, message, drawing or other subject matter is transmitted by facsimile signals generated in accordance with the subject matter appearing on an original sheet or blank, and is reproduced in facsimile upon a, recording blank which may, if desired, comprise a stencil or other master blank from which a large number of copies may be made by variousv'known printing or other duplicating processes. The recording blanks are carried by copyholders, such as rotatable cylinders or drums, that are scanned by the recording apparatus during the reproducing operation, and these copyholders may be interchangeableA in the apparatus so that they can readily be placed into operative position in the recording apparatus and can readily be removed therefrom, either manually or autain a linear scanning speed of approximately 1530 inches pei` minute. Moreover, with the prior devicesit was necessary to maintain an undesirably high power value of the carrier current or other signaling currents employed for actuating the recording stylus, and the amplitude of the stylus swing and the frequency response characteristic of the unit were not uniform when producing stencils.

Qne of the objects of the present invention is the "provision of facsimile` percussion recording apparatus which operates satisfactorily at arate such that the linear scanningspeed at which the recording is effected may be greatly increased,

and thus appreciably reduce the time required for producing a stencil or otherwise recording a given piece of subject matter. In the case of commercial telegraph circuits employed for transmitting facsimile messages from one city orpoint tomatically. The recording operation is effected by means of a suitably actuated recording stylus of the percussion type, i. e., one which intermittently contacts the recording sheet in accordance with the transmitted subject matter, thereby to change or affect the surface of the recording sheet to record thereon in facsimile the transmitted subject; matter.

In recorders of the character heretofore employed for producing facsimile stencils and the like, the percussion recording stylus was actuated by an electromagnetic device which responded only to the direct current components of the signaling currents or to direct current impulses produced in accordance with the received signals. Such devices, however, are undesirably limited with respect to the recording speeds at which they may satisfactorily be operated. In commercial operation it was found that, with va recording drum having a circumference, for example, of the order of eight and one-half inches, the speed of rotation of such a, drum necessarily was limited by the recording speed of the percussion unit, and could not wellbe increased in excess of .approximately 90 R, P. M., which meant a linear scanning speed of approximately 765 inches per minute, whereas it is desirable to usey speeds commensurable with those obtainable by electrosensitive recording blanks, for example, drum speeds of the order of 180 R. P. M., and thus obto another, it will be appreciated that any resultant saving in line time is of highest importance, and appreciably reduces the cost of such service. In accordance with the instant invention a percussion stylus is actuated by a piezo-electric device which is so constructed and operated that the linear scanning speed of the recording drum may be increased to speeds as high or higher than twice the linear scanning speed heretofore obtainable with prior percussion type devices, and thus substantially cut the necessary transmission time in half or less. Also, where a combined transmitter and recorder apparatus is employed in an oilice for producing stencils and the like, the time required for producing them may be approximately cut in half or less.

Another object of the invention is percussion recording apparatus of the character disclosed in which highly satisfactory recording is obtainable with much lower levels of the signal carrier current than heretofore and in which a signal modulated alternating current, Which may be a frequency modulated carrier current, may be directly impressed upon the stylus-actuating device.

A further object is a recording unit in which the recording point of the percussion stylus may be made exceedingly small without penetrating the surface of a. stencil sheet beyond a desired extent,

and in which the stylus may be actuated at much A further object is a percussion type facsimile recording apparatus 4which may be operated at greatly increased speeds of recording w1thout any stability of adjustment of the recording unit and greater uniformity in results are obtained.

A. still further object is a recording unit in which less precision is required in the manufacture of the recording drums employed, and in which less attention need be paid to uniformity of thickness of the recording stencils or blanks and in which irregularities in the recording blank surfaces are less likely to deleteriously aiect the record.

An additional object is to provide a percussion type facsimile recording unit which causes the darker areas of the recorded subject matter to be reproduced with greater clarity and detail.

The foregoing and other objects and advantages of the invention will appear from the following description of the illustrative embodiments of the invention, taken in connection with the accompanying drawings, in which:

Fig. 1 is a view oi' a combined transmitter and recording apparatus in which the recording apparatus is constructed in accordance with the present invention;

Fig. 2 is a view, in elevation, of the recording apparatus, taken along the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary top plan view of the recording unit employed, illustrating certain details of-the stylus driving unit and the manner of mounting the same;-

Flg. 4 is a detail in elevation taken along the line 4-4-4 of Fig. 3;

IaiFiga. 5 is a detail taken along the line 5 5 of si MF1? 6 is a detail taken along the line H of Fig. 'Hs a perspective view of the piezo-electric `stylus driving unit removed from its casing; and

Fig. 8 illustrates diagrammatically a circuit arrangement may be employed with the transmitter and recorder apparatus of Fig. l.

Referring .to the drawings, and particularly to Fig. 1 thereof, a base 20 forms the principal support for the apparatus and the driving and control mechanism therefor, which base is adapted to rest upon an apparatusv table or cabinet or other convenient support, and a cabinet preferably being employed so that certain of the power unit land amplifier devices used may be embodied therein.

Secured to plates a and 2lb on the base 2l are brackets 2l in which are mounted a front track or guide rail 22 and a rear track or guide rail 22 which slidably support the longitudinally movable transmitting scanning assembly 25 and the recording scanning assembly 20. Preferably, the transmitting scanning unit 2i comprises an optical pickup system for deriving facsimile s18- nals from an original blank 2l which carries the subject matter to be reproduced or duplicated, the blank being secured upon a cylindrical drum portion il of a copyholder which is indicated in its entirety by the reference numeral 3 l. The copyholder 3l includes'a cylindrical drum portion I4 adapted to support a recording blank or stencil blank 8l which is acted upon bythe percussion stylus 33 of the recording' unit 2i. In general. any suitable means for scanning the transmitting and recording blanks may be front guide rail 22.

employed, for example, as disclosed in the dHumy et al. Patent No.v 2,301,024, issued November 3, 1942, or in the OBrien and Estes Patent No. 2,260,862, issued Oct. 28, 1941. Also, any suitable type of transmitter may be employed for generating the facsimile signals supplied to the recording unit, such for example as illustrated in Patent N0. 2,158,391, issued May 16, 1939, and

Patent No. 2,176,442, issued October 17, 1939.

'I'he transmitting scanning assembly 2B and the recording unit 26 are respectively mounted on traveling bases or carriage members 36 and 31, which latter members are each provided with guide blocks 38 and 39 slidably mounted on a The carriage members have rollers 40, one of which is shown in Fig. 2, that cooperate with the guide rail 23 to facilitate travel of the units 25 and 20 along the guide rails. The carriage member 31 of the recording unit is connected to the carriage member 3B of the transmitting unit, as by acarriage link 42 firmly 'secured to portions 36a and 31a of these units,

so that any movement of the recording unit Il longitudinally along the guide rods 22 and 2l will impart a similar movement to the transmitting unit 25, and vice versa. The various mechanical details for thus interconnecting the transmitting and recording umts so as to cause them to operate in synchronism with respect to the line feeds thereof are disclosed in detail in my said copending application, and for the sake of brevity certain of these details are not illustrated in the drawings herein.

Power for operating' the apparatus is supplied lby a motor contained within a casing 40, the motor preferably being of thesynchronous alternating current type, although if desired may be of the direct current type, it being understood that the speed of the motor for any given operation may be adjusted and maintained constant by any of the various suitable means known in the art for this purpose. The power is applied by the motor through the medium of reducing gear mechanism in known manner, which gear mechanism is also contained within the casing 40, the

motor and gear mechanism causing rotation of the driven shaft 4I which rotates the transmitting and recording drums Il and 34 in the direction indicated by the arrow on drum ll during the scanning operations. The gear mechanism also drives a line feed shaft 43 which has a threaded portion 43a that directly drives the recording unit 26, and through the medium of the carriage link 42 also drives the transmitting unit 26 to cause line feed scanning movement of the units with respect to the transmitting and recording drums Il and 34. l f

PreferabLv, and as disclosed in my aforesaid copending application, the apparatus is arranged to accommodate transmitting and recording drums of different diameters in order to accommodate transmitting and recording blanks of different sizes, and for this reason the gear mechanism within the casing 4l is adapted to be shifted, as by the gear shift lever 42, in order to provide different driving speeds to the drums and therefore change at will the peripheral speed of rotation of the drums Il and 34. With the drum speed shift arrangement the linear scanning speed for the drums Il and 34 may be changed if desired, or when drums of different diameters are used in place of the drums shown the number of revolutions per minute of the drums may be either reduced or increased to an extent such that the peripheral speed of rotation and hence the linearscanning speed .will remain approximately the same irrespective of the size of drums employed. Also, the driving ratio of the searsl gear ratio may be such that'the number of'scanning lines may be increased to 120 lines per inch, the arrangement enabling'the number of scanning lines per inch to be made such as to give the most desirable results depending upon the subject matter and the kind of service for lwhich it is used.

If desired, and as described in detail in my position when the handleis turned downwardly, the spring also causing the bearing member 4l to enter the end 41 or the cylinder thereby to insure that the cylinder is properly supported during rotation thereof and to maintain a proper driving connection between the members 4l and 48. Instead of employing a cylinder Il having theI transmittins and recording drums formed or mounted thereon, separate transmitting and recording drums may be employed and maintained in proper driving relation in the manner disclosed in my aforesaid copending application.

Fixed bracket members Il and il are provided, each of the bracket members comprising two arcuate supports or saddles. the inner pair of these saddles preventing the cylinder-'3| from dropping when it is released from the bearings 48 and V49 aforesaid copending application, two line feed shaft members similar to the member 4I, and which may be caused to operate at different speeds respectively, may be employed, one of which shafts produces the line feed scanning movement of the transmitter unit and the other of which produces the line feed scanning movement of the recorder unit, whereby when transmitting and recording drums of different diameters respectively are concurrently employed, the reproduced record may be enlarged or reduced with respect tothe subject matter on the transmitting blank withoutcausing distortion of the recorded subject matter. The foregoing various features of variable speed of theI transmitting and recording cylinders and their respective line feed scanning means `comprise subject matter claimed in my aforesaid copending application, and for the sake of simplicity such arrangements are n'ot disclosed herein in detail.

The cylinder 3l has reduced ends 45 and 41 formed with internal tapered surfaces which receive complementary bearing members 48 and 49. The. bearing member 48 is secured to and driven by the shaft 4I hereinbefore referred to. and serves to drive the cylinder 3l. The member 48 is secured to a shaft 5l journaled in` fixed uprightibearing members 52 and 53 so as to be freely rotatable and also slidably movable longitudinally within 'the bearings to permit entry and withdrawal of the member 49 from the recessed portion of the 'end 41 of the cylinder 3i, and thereby permit ready insertion and removal of the cylinder 3| and drums 30 and 34.

To facilitate the insertion and withdrawal of the member v49, preferably there is provided a tapered cam member 55 flxedly secured to the bearing support'SZ, and coacting with this cam member is a second tapered cam member 56 which is secured, as by a set screw, to the shaft 5I. Se

'cured to the cam member 56 is a handle 51, and

when the handle is raised upwardly as viewed in Fig. 1, this causes rotation of the cam 56 relative to the xed cam 55, the adjacent tapered camming surfaces of these members coacting to cause the member 5E to be shifted to the right as viewed in the figure and thereby -cause longitudinal movement of the shaft 5| and withdrawal of .the bearing member 49 from the recessed end 41 of the cylinder 3|, after which the cylinder may be slid to the right a distance sufficient to release the opposite end 46- from its associated drive member 48. A compression -spring 58 which loosely surrounds the outer end of the shaft Il. causes the member 58 to return to the working -and gthe outer pair of saddles providing a convenient rest for the cylinder Il to enable the blanks to be applied to and removed from the drums 3l and I4 at the beginning and termination of a reproducing operation.

As hereinbefore stated. any suitable transmitting unit may be employed. In general, in an optical pickup system such a transmitting unit employs a lens tube li containing lenses and an apertured plate aligned in position with respect to each other so that light from an exciter lamp is concentrated on a minute spot on the periphery of the drum Il and consequently on elemental areas successively of the subject matter sheet 29 thereon during scanning. Another lens tube 61 contains lenses for directing the beam of light reflected from the elemental `area of the record sheet 2l at the time being scanned onto an aperture and thence to a photocell, a light chopper in the form of a perforated disc being interposed between the photocell and the aperture in known manner, the number of perforations or notches in the disc and the speed of rotation thereof depending upon the desired rate of scanning, the

' frequency of the signal carrier current employ-2d,

and other` factors. Preferably, and as disclosed in said Patents 2,158,391 and 2.176.442, the transmitter employs two light sensitive cells associated with the light chopper disc or discs in such manner that the signals produced by the transmitter need notl be inverted before application to` the recorder in order to provide a positive record from a positive original blank or a negative record from a negative original blank, although if desired one light sensitive cell may be employed and the signals inverted either in the transmitting or recording circuits by means of suitable signal inverters of a type well known in the communication art.

It is essential that the transmitting scanning apparatus and also the recording scanning apparatus be accurately positioned with respect to the spacing between the scanning elements of these units and the blanks containing the subject matter thus transmitted and recorded. For this purpose the transmitting unit 2l is mounted so as to be adjustable towards and from the drum 30, and its operative position may readily be adjusted as by rotation of the knob Il and rod 68a to which theknob is secured, thereby to provide a proper' ustlnent or spacing between the transmitting scanning elements and the blank 29 on the drum irrespective of the size of the transmitting drum employed. A relatively fixed plate is provided which bears indicia such as the letters A, B, C. which respectively correspond to three diierent sizes of transmitting drums that may be emplayed, theknob Il being turned until-a pointer two plates are parallel.

It carried bythe transmitting scanning unit is opposite the mark corresponding'to the particular size of the drum to be used. A graduated drum or vernier Il is provided for enabling a micrometer adjustment of the scanning' elements o! the optical pickup system relative to the scanning sheet. The foregoing adjusting members are disclosed in detaill in my said copending application.

The recording stylus actuating device is enclosed in a casing ll. Figs. l, 2. 3 and 5, the casing having mounted therein a composite piezo-electric element which may be built up from two similar crystalline plates 'il and 12, Figs. 5, 6 and '1, of homogeneous piezo-electric material assembled as shown in Fig. '1. These plates may be cut from a Rochelle salt crystal, in a manner well known in the piezo-electric crystal art, for example, with their extended plane surfaces substantially perpendicular to the electrical axis so that the directions of expansion and contraction of the plates when subjected to an electric ileld are at substantially 45"A to the major longitudinal axis, or the plates may be cut so that one of them has a longitudinal dimension parallel to the major longitudinal axis of the crystal and the other with its longitudinal dimension parallel to the major transverse axis of the crystal, or the plates may be cut so as to have their longitudinal dimensions parallel to the major transverse axis or so that the plates have their longitudinal dimensions parallel to ythe major longitudinal axis.

When plates are cut from a crystal in the manner indicated above and subjected to an electrostatic field in the direction of the electric axis, the plateswill expand on lines parallel to their faces at an `angle of substantially 45 to the major longitudinal axis and will simultaneously contract along lines parallel to their faces and at substantially 90 to the lines of expansion. Thus, if the different plates are properly arranged with their indicated by the dot-and-dash lines in the figure.

The plates 1I and 12 together with their electrodes 13 and 1l preferably are cemented together throughout their adjacent surfaces and along their edges by a suitable cement, the iixed end of the assembly also being secured to one end of the casing 10 by a suitable cement. As shown, resilient pads 80 of sponge rubber or other suitable material may be disposed between the fixed ends of the crystal plates and the casing 10, which pads protect the piezo-electric unit from mechanical shocks and jars and form a cushion therefor during the normal operation of the recording stylus. These pads of sponge rubber or 'the like also press the plates 'firmly together and "causes the point of the stylus to impact the stencil sheet in a direction substantially normal to the surface of the sheet, the length of the stylus also multiplying the movement imparted by the free end of the crystal unit so that such movement is increased to an extent suiilcient to provide proper oscillatory movement of the stylus against the stencil or other recording blank. The stylus 3) is held in the recessed portion 'i9 of the unit by means of a. wedge-shaped member IlA that .has "a Wedge-.shaped or knife-blade line bearing surface 82, Fig. 6, which contacts the stylus 33 in such manner that the `sty1us is firmly heldagainst the crystal and yet does not interfere with the longitudinal axes parallel and subjected to electrost'atic fields in the same direction, the expansion of each plate will take place on lines parallel to the contraction of the other plate, and whenJ the direction of the electrostatic fields is reversed.

the plates will contract on the lines on which they formerly expanded. and vice versa.

The plates preferably are assembled as indicated in Fig. 'l and are provided with electrodes 13 and 1|, the electrodes comprising tin foil applied to the sides of the plates and secured thereto in suitable manner, as by cementing. The two inner electrodes ll are in electrical contact with each other and connected to the incoming signal circuit by means of a common conductor 1B, and the outer electrodes Il are connected together and to vthe other side of the signal circuit by means of a conductor 11, and in such an assembly the directions of expansion and contraction of one 'platen are respectively opposed to the directions of con-- traction and expansion of the other plate when the corresponding maior crystalline axes oi' the When these plates are subjected to electrostatic nelds by means. of the signal currents applied to conductors "and 'Il and the electrodes Il and 1I, the plate 1|, for example, tends to expand along the same lines as theplatelltendstocontractandbecauseofthe mutual constraint of the plates the assembled element twists or cillates about its central longitudinalaxismif'oneendoftheplateassembly, suchasthelefthandendasviewedinli'i8.7,is

' heldin anysuitablemannenthefreeendportions ofthe plates tend to have the twisting movement desired vibratory movement of the crystaland stylus in the proper direction to effect recording. A threaded adjustment screw 83 adjusts the position of the wedge 8l and also the degree of pressure exerted by the wedge-shaped bearing portion 82 against the stylus.

It is to be understood that the piezo-electric actuating unit may differ in character from that specically described above, various other forms being well known n the piezo-,electric art. For

example, and by way of illustration only, the

v stylus actuated therebyl having the proper configuration so that it will impact on the surface of the record sheet in the proper direction to produce the desired record thereon;

'I'he casing 'Ill is secured to a plate 8l; the ends of the plate being pivotally mounted by pivot screws 85, Fig, 3, and thus the recording unit is hingedly mounted so as to enable the same to be freely movable in a direction transverse to the recording surface of sheet 35. 'I'he pivot screws 8l are mounted in bearings I6, which bearings are secured to a plate member I1, the latter member beingl secured to a support Il of the scanning mechanism, as seen in Figs. 2 and 3. The supporting plate Il is mounted on a plate 89 which is adjustable to adjust the position of the recording unit towards and from the recording drum in a manner hereinafter explained.

The unit 10 carries a stylus-positioning member or shoe ll, this shoe memberY being secured ciently large to enable free movement of the` stylus during recording operations. The -,shoe

vmember 9| has an upstanding formed or bent to the point of the stylus during recording.

Theshoe member 9| is adjustable relative to l the casing 10 by means of an arm 94 and a screw 95 which is threaded into a U-shaped frame member 96, the frame member 96 being secured as by screws 91 to the plate 84. The adjusting arm 94 is clamped as by means of a screw shown in Fig. 3 to the adjusting screw 95.

A knurled counterweight |00, Figs. 3 and 4, is adjustable longitudinally on a threaded rod and urges the portion 93 of the shoe 9| into engagement with the recording blank in such manner that the degree of pressure exerted by the shoe on the blank may be controlled within very close limits.` The rod |0| has one endthereof secured to and carried by ablock |03, the block being held by a U-shaped member |04 which is pivotally mounted on a pin |05 that is securedv to a bracket |06, the bracket |08 being secured to the plate 88 by screws |01. Member |03 of the threaded rod |0| carries a rubber cushion or damping member ||0 which directly engages the plate 84 and causes resilient pressure to be eX- erted thereon for maintaining the shoe 9| against the surface of the recording blank.

The foregoing arrangement insures that the recording stylus will accurately follow, and be properly positioned to impinge on, the surface of the recording blank with the proper extent of movement and pressure at' all times during recording, irrespective oflirregularities in the thickness of the recording blank or stencil or ir,- regularities in the surfacethereof such as may. be due to overlapping portions of the blank or to the character of the paper or other material of the blank or stencil or due to irregularities in the ooniiguration or movement of the recording drum 34, and thus satisfactory recording is effected with greater permissible tolerances in the manufacture of both the recording blanks and the recording drum or other platen member employed, the arrangement being advantageous with an electromagneticaily actuated stylusl as well as one actuated by a piezo-electric element.

Mounted on plate 84 is a bracket ||3 held by screws H4, the upperportion of the bracket ||3 having thereon a line or groove I5. The member |06 has a similar line or groove H3, and the sliding plate member 89 is adjusted inwardly or outwardly by an adjusting screw-threaded shaft |23, Fig. 2, which is threaded into the member 89. The groove portions I5 and ||3 are so positioned that, when the unit isl in proper recording position, they coincide to give a ready and accurate indication of this fact. Interposed between. the members 88 and 89 is a spacer plate |20 to give the desired height tothe recording unit. The member |06 carries a stop pin H1, Figs. 3 and 4, which serves as a stop for the unit 10 to limit the forward permissible movement of ,the unit. The rod being rotatable by the knurled knob |23a to adjust the recording unit to any of the desired positions, such as indicated by the indicia A, B and C that appear on a plate member |22 secured to the carriage of the recording unit, the indicia respectively corresponding to three different sizes of recording drums that may be.

employed. A graduated dial or vernier |24, Fig. z, secured to the rod |23 enables very vaccurate adjustment of the recording stylus 33 relative to une Arecording blank or stencil. A pointer |25 carried by the member 88,' Fig. 3, coacts with the plate |22 bearing the indicia to indicate when ne leeordlng unit is adjusted for the size ox drum to be employed. The method of thus adjusting the recording unit is described in detail in my aiolesaid copending application.

The line reed or' the transmitting and recording is effected bymeans of a split block assemblyj comprising identical opposed split halves |50, rig. 2, which members are internally threaded to receive the feed screw thread 43a, the members being spring-pressed into engagement with the threads of the feed screw by means oI four compression springs. |3| which act betweensupport members |32 and |33 anu` the upper and lower portions 0f the members |30. 'ihe members |32 and `|33 comprise tne legs or a U-snaped bracket which is secured 4to the recording unit carriage. Interposed between the inner tapered surfaces of the opposite ends of members |30 are two wedge-shaped members |35, the lower members |35 being secured to a split-nut release lever rock shaft |33, and the upper wedge-shaped member |35 being mounted on a rock shaft |31. shaft |31 is operatively connected to the shaft |36 by means of gears |38 and |39. When the handle |36a, Fig. 1, of the shaft |36 is rotated so as to turn the wedge-shaped members. |35 from the positions in which they are shown in Fig. 2, rotation of these members forces the split-nuts apart a sufficient distance to effect their release from the threaded rod 43a and thus enable both the transmitting and receiving units as their initial starting positions, after which they rod |36 is again turned in a direction such that the wedge-shaped members |35 assume the positions shown in Fig. Zand again make efi'ective the feed screw 43a.

In order that there may be no likelihood of injury to the recording blank or stencil by the stylus 33 or injury to thepoint of the stylus y ment of 'this core, due to energization of the solenoid |45, causing corresponding movemenjl ofa pin member |44 secured thereto. The pin |48 is positioned within a slot in a post' member |49 secured to a slidable block |5I, and through the member Il andthe rod |23 causes withdrawal of the stylus a predetermined distance from the Member |35 on recording drum when the solenoid |45 is energized by closure of the switch |44, the limit of this retracted movement being determined by the core |41 strikinga stop member |52 on the frame of the solenoid i45 when the stylus is in its proper retracted position. i

The plate |53 comprised in the solenoid structure supports a bracket member |54, the plate |53 being secured to a block |55 mounted in guide members |56. Bracket |54 carries a dashpot |51, the plunger |58 of the dash-pot being received within and actuatable bythe upper end of a bracket member |59, the bracket |59 being secured to the block A retractile spring |6| serves to urge the` recording unit towards the drum 34, the movement of the recordng unit in this direction being limited by engagement oi' the inner end of the knurled knob |23a with the end of the member |53. The dash-pot |51 eases the impact of the stylus with the drum when the magnet |45 is deenergized, the dash-pot insuring that the stylus will'gently contact the recording blank on the drum 34.

The original copy sheet 29 is wrapped around the transmitting drum 30, Fig. 1, preferably in such manner that the top of the copy is at the left hand end of the drum when facing the machine, the right hand edge of the copy overlapping the left hand edge by a slight margin. The copy may be held in position by any suitable means, such as an elastic band or garter |15, which preferably comprises a helical spring in the form of an annulus, such as disclosed in Patent No.12,255,863. As shown in the figure, the leading garter member is advanced axially along the drum 30 from the left toright as scanning proceeds by a garter pushing plate member |16 secured to the supporting frame 36, and

.quency representing a black or marked area is the ,trailing garter member is advanced by a are kept immediately adjacent to the place where received, the stylus unit will vibrate at maximum amplitude and cause marking impacts to be applied to the recording blank, whereas when a signal frequency representing a light or unmarked area on the-transmitting blank is received, which frequency is substantially different from the resonant frequency of the stylus unit, the amplitude of vibration of the stylus will be insufllcient to cause marking impacts to be applied to the recording blank, and the record receved will be delineated in black' and white as determined by the diierent frequencies respectively of the incoming signals. If but one fre-l quency is employed, the unit will respond to the amplitude modulation of such frequency, as determined by the marked and unmarked areas on the transmitting blank. To facilitate inspection of the actuating unit, the casing 10 has a slidable plate 10a, Fig. 3, which is received within grooves in the top of the casing, the plate being slidable to the left as viewed in the figure, after the stylus has been removed, to expose the crystal assembly within.

Referring to Fig. 8there is shown a circuit arrangement suitable for interconnecting the transmitting and recording apparatus in accordance with the present invention, although other known electrical systems. suitable for transmitting and recording in facsimile may be employed, depending upon the purpose for which the apparatus is to be used.' At the transmitting end a scanning photoelectric cell 200 and a balancing photoelectric cell 20| preferably are employed in the manner set forth in the aforesaid Patents Nos. 2,158,- 391 and 2,176,442, and controlling the light applied to the cells is a light chopper 202 which is rotated at a constant predetermined speed by a motor in a manner well known in the art. In the embodiment shown the speed of the light chopper preferably is of the order of 3300 R. P. M. so that the apertured portions thereof will produce a carrier frequency of the order of 2500 cycles.

scanning is being eected, the bands rolling along on the copy sheet as the scanning proceeds and holding the copy sheet tightly against the drum andpreventing distortion in the optical scanning system which otherwise might occur if the copy was not held tightly against the drum. Two similar garter members |15 are employed to hold the recording blank or stencil 35 on the recording drum 34, and usually these members may be placed adjacent to the ends of the blank 35, as indicated in Fig. 1.

Preferably, the resonant frequency of the'stylus actuating unit, including the stylus, is made substantially to equal the carrier frequency employed. The desired resonant frequency of the unit may be predetermined either empirically or by calculation so that it is approximately the same or less than the carrier frequency and a small lump of solder |50, Fig. 5, may be applied'to the stylus 33, after which the solder may easily be led and reduced in mass until the resonant frequency of the unit including the stylus has the desired value. Due to its'selective characteristic the unit will respond either to amplitude modulated signals or frequency modulated signals since it discriminates with respect to both frequency and amplitude modulation. If, for example, an

When light is falling on both photocells, the signal amplitude is at a minimum due tothe balanced arrangement of the cells, and no signal is transmitted at this time. When a black mark appears under the scanning ray, howeventhe two photocells become unbalanced relative to each other and at this time there is transmitted a carrier frequency of 2500 cycles which carrieriis modulated by the appearance or non-appearance of a mark on the original copy. This modulating frequency depends upon the speed at which the white andv black elemental areas pass by the scanning light. For example, with an elemental alternating current is employed whose frequency I is modulated in accordance with the black and white areas of the subject matter scanned on the facsimile transmitting blank, when a frearea of approximately eight circular mills where the scanning ray impinges on the subject matter appearing on the transmitting blank, and a drum of eight and one-half inches in circumference and a speed of R. P. M., the carrier frequency will thus be modulated by a signal frequency of the order of 1400 cycles. In the circuit of the balancing photocell is an adjustable impedance or resistance 204 which enables the photocells to be accurately balanced with respectto each other so that each one puts out the same amplitude of signal. It will be understood that the phase relation between the two light beams for each of these photocells will be so adjusted as to most effectively balance when the scanning light is on the white background, as described in detail in the aforesaid patents.

The signal output from the photocells is con nected to a pre-amplifier 203 of known type, and

the transfer of signals from this amplifier 202 to the succeeding ampliiler stages is controlled by a gain control device 205. Connected to the gain controlv device 200 are two'ampliilcation stages comprising the Lpentode tubes 201 and 255. In both the pre-amplifier 252 and the two-stage am- .piiiler 201, 205, the constants ofthe circuits, in-

cluding the coupling condenser 2 Il, are such that the amplifiers will not pass low disturbing frequencies caused by undesired pickup from interfering stray fields. The amplifiers preferably are so designed that they will pass frequencies principally in the band from 1000 to 7000 cycles, whereby the unit may be adapted to operate with carrier frequencies of from 1500 cycles to 5000 cycles. the type known as the 68.17, although other equivaient types of ampliiier tubes may be employed. The amplifier tube 200 preferably is of the type known as 6K6, although here again a tube of different type may be employed so long as it is suitable for the purpose. All stages of the ampliiler including the pre-ampliiler 252 are of Class A ampliilcation, whereby each tube has a constant average plate current loutput regardless of the amplitude of signal applied toit.

Connected between the cathode and grid of the amplifier tube 251 is a self-biasing arrangement comprising a condenser A2| I, which may be of the order of 25 microfarads, and a resistor 2 I2, which may be of the order of 3000 ohms. The screen grid of the tube is connected with a series resistor 2|3, this resistor being shunted by a ily-Dass condenser 2 I4. Connected to the plate circuit of tube 2,01 is a couplingresistor 2|5 whichis connected to ground through a condenser 2|5. A

resistor 2|1 is connected in the plate circuit of tube 201 to give the desired plate voltage, the resistor also coasting with the condenser 2|! to filter out variations in the plate supply current. The output of the amplifier Y201 is applied to the input of amplifier 250,"resistance 225 -providing the proper grid leak resistance for the latter tube. 'Ihe tube, as shown, may employ a self-biasing arrangement in the manner of tube 251.

The output from amplifier stage 205 is'applled, through atransformer 222, to a switching system employing a double-throw switch 224, which, in

the position shown, connects the amplifier stages 201 and 208 to a second transformer 225. The secondary of the transformer 222 is also' connected to a test jack 225 which, when a plug is inserte/d therein, enables the decibel readings of the power level of the signals to be determined. vConnected in circuit between the windings of transformers 222 and 225 are a tuning condenser 221 and an impedance 225, thereby to make-the transformer circuit contribute to a more desir-A able frequency characterlstic and widen the fre- Acuency band forthe purpose of accommodating the higher modulating frequencies andthu's obtain better detail in the recordproduced. The

. switch m is provided to enable the recording 'apparatus to be employed either with the transmit-V ter shown at the left of Fig. 8, or to enable signals received from an incoming line to be applied to the recorder, the latter circuit being effective when the switch 224 is thrown upwardly to contact the terminals of the incom- The output ot transformer 22a is applied tn two amplier tubes 22l-and 25| connected'in a pushpull arrangement. and the output of these tubessupplies the driving energy for the recording unit The ampliiier tube 251 preferably is of plied, by means of a transformer 245, directly to the piezo-electric unit 10, which unit is responsive to the alternating modulatedcarrier current thus impressed.` thereon in accordance with the received signals.l As shown, the tubes 230 and 23| in the last amplifier stage may be self-biased by means of a midpoint tap 235 to the transformer 240 which supplies the diament current. this midpoint tap being connected to ground through a suitable resistance 234. As indicated in the drawings, the power stage 230, 22| is suppliedwith separate source P of `iilament and plate voltages to avoid feedback between the ditferent lamplifier stages which might occurl if the same power pack were employed for all the am'- plifier tubes.

The resistance 242 is connected across the output of the transformer 240, the resistance having a value suiiicient to stabilize the voltage applied across the terminals of the recording unit 10. A voitmeter V in the output circuit of the last amplifier enables the operator to set power levels and also facilitates balancing of the photocells of the transmitter. It will be understood that the load presented by the recording unit 10 to the amplifier output is practically that of the capacitive reactance, the unit being a voltage actuated device in which there is a stra-ight line relation between voltage and stylus deilection.

Where the' signals for operating the recorder are received from an incoming line, which may represent a circuit originating in another city or different locality from that of the'recording unit, it will be understood that the incoming signals are suitably ampliiled prior to their application to the push-pull ampliiier stage shown. and that these signals may be amplified either at the place of origin, at the receiving end, or intermediate these points.

In order to save operating time and cause the scanning operation by the transmitter to stop approximately as soon as the subject matter on the original blank has been scanned, irrespective of the length of the blank as measured longitudinally along the transmitting cylinder, a switch 250,

' Fig. l, is provided, which switch may be mounted on the traveling carriage of the recording unit 10, the switch being connected, as by a exible cord, in series with a carriage limit switch 25|. Either of the switches when operated -to open circuit position will cause the driving motor and hence the scanning units w stop. Coacting with the switch 250 is an actuating unit 252 therefor which, as shown in Fig. 1, may comprise a collar or sleeve member 255 that has a relatively close nt with the guide rod' 23 on which itls mounted, the member 255 being slidable longitudinally along the guide rod and thus readily settable to different machine stopping positions corresponding to various positions of the transmitter at the .time' the subject matteron the transmitting blank `the switch m. when the une feed movement or the transmitting carriage has caused the latter 1|. 'me output or the tube; zu and all is ap- 7s t0 completely mn the wbiect rustici' 0n the 2,260,8162 and 2,301,024.

The unit 253 is manually set by the operator y prior to the scanning operation of any given subject mattei', and to determine readily the setting to which the unit should be placed, there are provided corresponding calibrated scales Nl and 26|, whereby the operator may place the subject matter sheet on the transmitting drum and visually discern the proper mark on the scales III, and then set the unit 253 to the corresponding scale setting. In the event that the unit III is not initially Set r is improperly set, a rod 2 secured to the recording ca age unit will engage the carriage limit switch l t and automatically stopthe driving motor and the transmitting and recording apparatus so that no iniuryvcan occur either to the scanning apparatus or tothe recording sheet or stencil by reasony of overtravel of the scanning units.

In order to prevent injury or shock to the transmitting and recording units when they-are moved to their initial starting-positions, there is provided a buffer in the form' of a dashpot IILfFig. l,

mounted on the frame structure Ila. the dashpot having a plunger lll which'is held in its exasrasss instrumentality responsive to a carrier current ci a predetermined frequency which is modulated by a signal frequency in accordance with the elemental areas of the subject matter to be recorded, said copying instrumentality having a percussive recording stylus and a piezo-electric unit for actuating said stylus, means for causing said copying instrumentality to scan the record sheet, and means for applying said signal modulated carrier to the piezo-electric unit to cause the recording stylus intermittently to oscillate and cause markingimpacts to be applied to said sheet substantially at the frequency ofthe applied carrier and produce thereon a facsimile record in accordance with the signals represented by said modulated carrier.

tended position by a compression spring within that it prevents undue shock to the units, the f structure also providing a suitable 'means for limiting the extent of movement of the .units toward the left and determining the desired initial starting position ofthe unitsu V Other control circuits for starting and stopping therecorder; particularly when .it -is connected to an incoming line instead of to the transmitter as shown in Fig. 8, may of course be employed,` various kinds of which circuits Asuitable for the purpose are known in the facsimile recording art, for example, as shown lx1-,the aforesaid'Patents While the invention has been described in connection'with one illustrative form thereo f,'it will be evident to those skilled in the art thatvarious other forms and modincations may be .employed without departing from the spirito! the invention.

and therefore the invention 'is not limited Aexcept 'as indicated by the scope of the appended claims. wnstlsclalmedis: v Lapparatus for' producing in facsimile on a 3. Apparatus for producing in facsimile on a record sheet a copy of a. picture, drawing or other subject matter, comprising a facsimile copying unit responsive to an alternating current of a predetermined frequency which is modulated by a signal frequency in accordance with the elemental areas of the subject matter to be recorded, said copying unit comprising a' percussive recording stylus and a piezo-electric element for actuating said stylus, means for causing said copying unit to scan the record sheet, means for applying said signal modulated alternating current to the pielo-electric element to cause the recording stylus intermittently to oscillate and cause marking impacts to. be applied to said sheet substantially at the frequency of the applied alternating current and produce thereon a facsimile record in accordance with the signals represented by said modulated alternating current, the mass of said stylus and the frequency response characteristic of the piezo-electro element being such that the resonant frequency of said copying unit when in rerecordshcetaeopyoi'apicturedrawingorotheV subject comprising a `facsimile copyins instrumentalityy responsive to an alternating current modulated in accordance with theelemental vareas of the subject matter to be rscordedfsaid copying instrumentality having a persuasive re-` col-ding stylus and a piesoelec'tric unit for actuating stylus, means for causing said WW1!!! instrumentality "to scan the record sheet. and

means for alplying said 'modulated alternating currentto the pieno-electric unit to cause the reintermittently to oscillate 'and cause marking be applied to said sheet substantially akt the frequency of the applied alterhating current and produce thereon a facsimile record in accordance with the signals represented cording position substantially corresponds to the frequency of said first named alternating current.

(Apparatus for recording in facsimile on a record sheet a copy of a picture, drawing or other subject matter, having a platen for holding blanks during recording operations, a recording device, means for causing said device to scan the blank on said platen, said recording device comprising a composite plate built up of a plurality-of laminatlons each cutfrom a crystal of piezo-electric material, means for holding said plate so that a portion thereof! may deform and vibrate when oscillating potentials are applied thereto, means for applying received alternating current facsimile signals to opposite sides of said plate to cause said portion of, the plate to deform and vibrate with said vibratile'portion of the plate land actustable by said deformationof the plate, said p0rtion of the plate causing said stylus intermittently to oscillate and causev marking impacts to be applied to, said record sheet substantially at the frequency of the applied alternating current vto record thereon in facsimile the subject um mm# ww, y "'fwlmik www u escalating electrical potentials are applied there'.

to, means for applying received alternating current facsimile signals Ito'opposite sides of said plate to cause said portion of the plate to twist and lvibrate in accordance with the oscillating voltage changes in said signals, a stylus operatively connected with said vibratile portion of the plate and Vactuatable by the twisting movej ment of the plate, said twisting movement causblank onsaid platen, said recording device com-l prising a composite platebuilt up of a plurality of laminations each cut from a crystal of piezoelectric material, means for holding said plate so that a portion thereof may twist and vibrate when oscillating electrical potentials are applied thereto, means for applying received alternating current facsimile signals to opposite sides of said plate to cause said portion of the plate to twist and vibrate in accordance with voltage changes in said signals, a stylus clamped to said vibratile portion of the plate and actuatable by the twistcylinder, said recording device being mounted on a carriage, means for progressivelymoving said carriage longitudinally along said cylinder during rotation thereof to provide proper line feed of the recording device, said recording l.device comprising a percussive recording stylus and a piezoelectric unit responsive to voltage changes in incoming signals for actuating said stylus and causing it intermittently to oscillate and cause marking impacts to be applied to said record sheet inl accordance with the signals received, and means for maintaining the piezo-electric unit and recording stylus properly positioned with respect to the recording blanks notwithstanding irregularities in the surfaces of said recording blanks or thev message cylinder, said last-named means comprising mounting means secured to said carriage and holding said piezo-electric unit so that the same is movable freely in a direction to follow the surface of said record blank as it rotates during recording operations, and av member operatively connected to said piezo-electric unit and controlled by the adjacent surface of the blank ing movement of said plate, said stylus having a portion thereof formed to cause the free end of the stylus intermittently to oscillate and cause marking impacts to be applied to said record sheet substantially at the frequency 'of said applied a1- ternating current comprisingA the facsimile -signais in adirection substantially normal to the surface thereof to record thereon in facsimile the subject matter represented by said received signals.

'7. Recording apparatus for facsimile telegraphyy comprising means for rotatably supporting a message cylinder for holding blanks during recording operations, driving means for rotating the cylinder, a recordingde'vice and means for causing said device to scan the blank on said cylinder, said recording device being mounted on a carriage, means for progressively moving said carriage longitudinally along said cylinder during rotation thereof toprovide proper line feed of the recording device, said recording device comprising a percussive recording stylus and a piezoelectric unit responsive to -voltage changes in incoming signals for actuating said stylus `and causing it intermittently to oscillate and cause marking impacts to be applied to said record sheet in accordance with the signals received, and means for maintaining the pizca-electric unit and recording stylus properly positioned with respect to the recording blanks notwithstanding irregularities in the surfaces of said recording blanks or the message cylinder, said last-named means comprising mounting means secured to said carriage and holding said piezo-electric unitso that the same is movable freely in a direction to follow the adjacent surface of said record blank as it rotates during recording operations.

8. Recording apparatus for facsimile telegraphy, comprising means for rotatably supportiing a messageV cylinder for holding blanks during recording operations, driving means for rotating ,the cylinder, a recording device and means for causing said 'device to scan the blank on said for controlling at alll times during recording the operative position of said piezo-electric unit and the percussive stylus actuated thereby relative to the surface of the blank.

9|. Recording apparatusfocrfacsimiietelegraphy, comprising means for rotatably supporting a message cylinder for holding blanks during recording operations, driving means for rotating the cylinder, a. recording device and means for causf ing said device to scan the blank on said cylinder, said recording device being mounted'on a. carriage, means for progressively moving said carriage longitudinally along said cylinder during rotation thereof to provide proper line feed of the recording device, said recording device comprising a percussive recording stylus and a piezo-electric unit responsive to voltage changes in incoming signals for actuating said stylus and causing it intermittently to oscillate and cause marking impacts to be applied to said record sheet in accordance with the signals received, and means for maintaining the piezo-electric unit and recording stylus properly positioned with respect to the recording blanks notwithstanding irregularities in they surfaces of said recording,

blanks or the said message cylinder, said lastnamed means comprising means for hingedly mounting said piezo-electric unit on said carriage so that the unit is movable freely in a direction to follow the surface of said record blank as it rotates during recording operations, and a member rigidly secured to and carried by said piezo-l electriciunit andv controlled by the adjacent surface of the blank for controlling at all times during recording the operative position of said piezoelectric unit and the percussive stylus actuated thereby relative to the surface of the blank.

10. A facsimile recorder for producing a record sheet of a picture, drawing or othersubject matte, comprising a recording unit including a stylus and actuating means therefor responsive to signals representative of said subject matter for causing the stylus to apply marking impacts to said sheet and form a record in accordance with said signals, scanning mechanism for causing said recording unit to scan thev record sheet, said recording unit carrying a stylus-positioning member and being mounted on said scanning mechanism so as to be freely movable in a direction transverse tothe recording surface of the record sheet, and means urging said stylus-positioning member into operative engagement with said recording surface of the record sheet for ter, comprising a recording unit including a percussion stylus and actuating means therefor responsive to signals representative of said subject matter for causing the stylus intermittently to engage saidrsheet 'and form a stencil in accordance with said signals, scanning mechanism for causing said recording unit to scan the stencil sheet, said recording unit carrying a stylus-positioning member and being mounted on said scan'- ning mechanism sc as to be freely movable in' a direction transverse to the recording surface of the stencil sheet, and means urging said styluspositioning member Ainto engagement with said recording surface of the stencil sheet for causing the stylus of the recording unit to be positioned accurately with respect to the stencil sheet at all times during recording'and irrespective of irregularites in the recording surface of the sheet.

12. A facsimile recorder for producing a record sheet of a picture, drawing or other subject matter, comprising a recording unit including a stylus and actuating means therefor responsive to sig.

able in a. direction transverse to the recording surface of the record sheet, means urging said stylus-positioning member into operative engagement with said recording surface of the record sheet for causing the stylus of the recording ,unit to be positioned accurately with respect to the record sheet at al1 times during recording and irrespective of irregularities in the recording sur `face of the sheet, and means for adjusting thel position of said stylus-positioning member relative to the stylus to determine the operating position of the stylus.v

13. A facsimile recorder for producing a record sheet of a picture, drawing or other subject mat ter, comprising a recording unit including a stylus and actuating means therefor responsive to signals` representative `of said subject matter for causing the stylus to engage said sheet and form a record in accordance with said signals, a casing enclosing said actuating means, scanning mechanism for causing said recording unit to scan the record sheet, said casing carrying a stylus-positioning shoe member and being pivotally mounted on said scanning mechanism so as to be freely rotatable in a direction transverse to the recording surface of the record sheet, and means urging said stylus-positioning shoe member into operative engagement with said recording surface of the record`sheet for causing the stylus of the recording unitpto be positioned accurately with respect to the record sheet' at all times during recording and irrespective of irregularities in the recording surface of the sheet.

14. A facsimile recorder for producing a record v sheet of a picture, drawing or other subject matter, comprising a recording unit including a stylus and a piezo-electric element responsive to signals representative of said subject matter for driving the-stylus to cause it to engage said sheet and form a record in accordance with said signals, a vcasing enclosing said piezo-electric element, scanning mechanism for causing said recording unit to scan the record sheet, said casing carrying a, stylus-positioning shoe member and. being piv otally mounted on said scanning mechanism so as to be freely rotatable in a direction transverse to the recording surface of the record sheet, and ad justable means urging said stylus-positioning shoe member into operative engagement with said recording surface of the record sheet with a predetermined degree of pressure thereon for causing the stylus of the recording unit to be positionedV accurately with respect to the record sheet at all times during recording and irrespective of irregu- RALEIGH J. WISE. 

